Modbus Integration (BI - subsystem-specific extension)

Data type defines the data type for encoding the subsystem-specific data type.

16 bit integer data formats with Registers:

Encoding format

Description

Byte order

U16-B
U16-L

unsigned 16-bit; big-endian
unsigned 16-bit; little-endian

bb aa
aa bb

Bitset encoding order for Coils and Discrete Inputs

B1 … B8

- Coil / Discrete Input with the lowest address is encoded in the least significant bit_0.
- Coil / Discrete Input with next higher address is encoded in bit_1, etc.
- unused bit_n … bit_7 will be zero-filled.

B9 … B16

- The first transmitted byte will transport information of Coils / Discrete Inputs with the lowest 8 addresses.
- the Coil / Discrete Input with the lowest address is encoded in the least significant bit_0 of the first byte.
- the second transmitted byte will transport information of Coils / Discrete Inputs with the highest addresses, starting at bit_0.
- unused bits in the second byte will be zero-filled.

Example:
Request to read a series of 10 inputs starting at Input@ 20:
- The response data contents are two bytes: 0xCD01 (1100 1101 0000 0001 binary).
- The bits of the response value correspond to the inputs in the following way:

"Bit-Offset" defines an offset in reading bitset of data (Coils, Discrete Inputs). This allows to support mass manipulation/correction of data point addresses.

-1

0

100

"Polling times" defines the polling timer to be used to poll the subsystem-specific data point.

The interval values for T1, T2, T3 can be configured in the Fieldbus-Management-Object.
Heartbeat timers and Polling timers are independent from each other.

T1

Highest priority. Typical interval value: 0.5s...5s.

T2

Medium priority (default). Typical interval value: 5s…60s.

T3

Low priority. Typical interval value: minutes ... hours.